Drill.



I 1. n. MAcDONALD, DECD.

' F. C. MAcDONALD, ADMINISTRATOR.

DRILL.

APPLICATION FILED SEPT- 11. I912- Patented Nov. 14, 1916.

2 SHEET$SHEET I.

Am U0 6 Q @HV 1 r xvi 5:621: 6%M m 1. 0'. MAcDONALD, DECD.

F. C. MACDONALD, ADMINISTRATOR.

DRILL. I APPLICATION FILED SEPT. II. I912.

Patented Nov. 14, 1916.

2 $HEETS-SHEET 2.

. UNITED STATES PATENT OFFICE.

JOSEPH D. MAODONALD, F SEATTLE, WASHINGTON; FRANK G. MAODbNALD, ADMIN- ISTRATOR OF SAID JOSEPH D. MAQDONALD, DECEASED, ASSIGNOB OF ONE-HALF TO CATHRINE MAODONALD AND ONE-HALF TO FRANK C. MACDONALD, BOTH 0F SAN FRANCISCO, CALIFORNIA.

Specification of Letters Patent.

Application filed September 11, 1912. Serial No. 719,781.

To all whom it may concern:

Be it known that I, JosEPH D. MACDON- ALD, a citizen of the United States, residing at Seattle, in the county of King and State of Washington, have invented certain new and useful Improvements in Drills, of which the following is a specification.

The present invention pertains to improvements in drills, and more particularly to that class adapted for use in mining, stone drilling, and the like.

The drill is shown in the annexed drawings, wherein:

Figure 1 is a longitudinal sectional view of the drill and a portion of the engine or hammer casing to which it is attached; Fig. 2, a bottom plan view; Fig. 3, a perspective viewas seen from the under side, three of the four bits being omitted; Fig. 4, a vertical sectional view taken at right angles to that shown in Fig. 1, and more clearly showing the air discharge ports; Fig. 5, a like view taken on the line 5-5 of Fig. 6; Fig. 6, a cross sectional view taken on the line 6-6 of Fig. 5 looking down; Fig. 7, a perspective view of one of the bits; Fig. 8, a like view of the bit-locking plug or member; and Fig. 9, a detail sectional view-showing a modification of the invention.

The main object of'the present invention is to produce a drill inwhich the bits may be readily positioned and secured, and as readily released and replaced when neces sary or desirable. struction is such that the bits will be firmly held in place, and will not become loosened under the jar or impact of the hammer.

In the drawings, .1 denotes a portion of the engine or hammer casing, in the end of which is seated the reduced or anvil end 2 of the drill head or chuck 3, said head being secured in place in the member 1 by the usual cross pin or member 4. The head 3 is pro- .vided with a centrally-disposed recess 5,

which extends upwardly into the reduced portion 2, the outer or lower portion of the recess being threaded. Ports orpassages 6 extend from the upper end of the anvil portion 2 downwardly 'therethrough, terminat-- ing in angularly disposed passages or ports 7, which latter extend through the head 3, opening at their inner ends in the upper portoin of recess or chamber 5, while their lower ends open outwardlythrough the side walls I dlsposed and equally Furthermore, the con-' of the head 3, and

bit-seats. The outer end of the head 3 is also provided with a series of bit-seats, designated by 8, the seats havmg the form of undercut or dovetailed grooves or slots, said grooves being radially I spaced about the central chamber .or recess 5. The formation of the grooves produces a series of intermediate sect ons 10, the inner wall 11 of each section being formed upon a radius somewhat greater than that of the central recess or chamber 5.

In the bottom ,of each bit-seat 8 there is formed a groove 12, the groove being closed at its outer end and open at its inner end; that 1s to say, the groove opens into the chamber or recess5, but stops short of passmg through the 'outer wall of the head 3, fermmg as it were an abutment 13 for the pin 14 of the bit 15 when the latter is fully positioned. The bit, as will be seen, is triangular in cross section, and is of such size at its base as to make a relatively close fit with its seat when positioned, the pin 14 passing into groove 12 and coming into contact with the abutment 13 which precludes further outward radial movement of the bit. The ends 16 of the bit will preferably be inclined or given a spread, so as to produce a relatively long cutting edge 17, and likewise produce points 18 which latter facilitate the cutting action of the tool.

To secure the bits in place after they are positioned, I provide a plug 19, said plug preferably having an opening 20 extending centrally therethrough, and likewise provided with an external threaded section adapted to engage the threaded portion of recess 5. The outer portion or end of the plug 19 is tapered as at 21, and this tapered face bears against the adjacent inclined faces 16 of the bits when the plug is screwed outwardly, thereby forcing the pins 14 into close contact with abutment 13 and consequently looking all the bits in place; see Fig. 4.

By merely screwing the plug 19 inwardly to the position shown in Fig. 1 the bits may 'be removed, one at a time, by moving the Patented Nov. 14,1916. Y

In Fig. 9 a slight modification is illustrated. Under such construction the groove in the bottom of the bit-seat is omitted, and a stop-pin 22 mounted in the head extends above said bottom. The bit 15 has formed in its base two alined grooves 23 and 2- separated at their adjacent ends by an abutment 25 adapted to co-act with the pin, as will be seen upon an inspection of the figure in question. This construction likewise permits the bit to be removed and turned end for end, so that when one point becomes dull the other point may be brought into action, it being understood that the outer points, or those which cut the wall of the opening being formed, receive the greatest wear.

In the operation of the drill the air which is employed to actuate the hammer is diseharged into the casing or shell 1, passes Having thus described my invention, What I. claim is A drill comprising a head having formed in its outer end a series of dovetail grooves forming seats, said headlikewis'e having a centrally-disposed threaded opening; a bit for each seat, said bits being triangular in cross section and having their ends inclined outwardly toward the cutting edge of the bit; a pin carried by each bit upon its outer face, said pin, when the bit is seated, entering a groove formed in the base of the bit-seat, and adapted when the bit is moved outwardly to its full extent to contact with the end wall of the groove; and a threaded locking plug mounted in the central opening aforesaid, the outer end of the plug being tapered, and when screwed outwardly, making a close fit with the adjacent inclined ends of the bits and locking them in place.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JOSEPH D. MACDONALD.

Witnesses FRANK GRIFFIN, ADELBERT HART. 

